The present invention relates to a control device for controlling the air flow of air streams in motor vehicle air-conditioning systems. The device has a frame which can be installed in an air duct, and lamellae which are mounted pivotably in the frame at their ends. The lamellae dimensions are selected such that, in a closed position, they cover the through-passage cross section of the frame. At least one of the lamellae is driven by a cylindrical gearwheel located on an outer side of the frame, and all the lamellae are adjustable in the same direction.
A flow control device of this general type is known from DE 44 42 000 A1, which corresponds to U.S. Pat. No. 5,878,806, the disclosure of which is incorporated herein by reference. If it is the intention for the lamellae to be moved via a drive rather than by hand, then it is necessary, in the case of an electric drive motor, to provide a reduction-gear mechanism which converts the relatively high speed of the electric motor into the necessarily slow pivot movement of the lamellae. Thus, for example, with motor speeds of 700 or 1500 rpm, a reduction to approximately 2 rpm is necessary. This results in bulky gear-mechanism arrangements that take up a lot of space, which is especially at a premium in motor vehicles. Moreover, it is an expensive and complicated task to build in such gear mechanisms and also to connect a motor to said gear mechanism.
In another type of actuating drive (DE 27 00 928 A1), which is provided for controlling the air flaps in heating and air-conditioning systems of buildings, it is known to combine a reduction-gear mechanism combined with an electric motor. The drive unit is contained between parallel plates and is pushed, via a hollow shaft assigned to the last drive gearwheel, onto the spindle of one of the air flaps which is to be driven. The drive unit is borne by the spindle and is secured against rotation. The dimensioning of the gear mechanism is not critical in this case because the constricted spatial conditions of the actuating drives for motor vehicles mentioned in the introduction do not exist here. It is also the case that such drive units have to be attached to the air flaps as a last step, which is not readily possible in the case of flow control devices for controlling air streams in motor vehicle air-conditioning systems.
One object of the present invention is to provide an improved air flow control device for a motor vehicle heating/air-conditioning system.
Another object of the invention is to provide a more straightforward method of installation for the airflow control device for motor vehicles that has a compact construction which only takes up a small amount of space.
It is also an object of the invention to provide an improved motor vehicle heating/air-conditioning system.
In accomplishing these objects, there has been provided in accordance with one aspect of the present invention an flow control device for controlling an air stream in a motor-vehicle air-conditioning system, comprising: a mounting frame adapted for installation in a duct of a motor vehicle air-conditioning system; a plurality of lamellae mounted pivotably at their ends in the lateral sides of the frame, the lamellae having dimensions selected such that, in a closed position, they close the through-passage cross section of the frame; a connecting member for connecting all of the lamellae together so that they are adjustable in the same direction; an add-on housing detachably connected to one of the lateral sides of the mounting frame to form a compact structural unit therewith; an electric motor mounted in the add-on housing and having a drive output; and a reduction-gear mechanism comprising a plurality of cylindrical gearwheels arranged one above the other and of which the largest diameter is smaller than the axial depth of the frame, the reduction-gear mechanism being operative attached to the drive output of the electric motor and having a final gearwheel that rotatably drives at least one of the lamellae.
In accordance with another aspect of the present invention, there has been provided a motor vehicle air-conditioning system, comprising a housing defining an air flow duct, an evaporator located in the housing, a heater located in the housing and an air flow control device positioned in the air flow duct, wherein the air flow control device comprises a device as described above.
Further objects, features and advantages of the present invention will become apparent from the detailed description of preferred embodiments that follows, when considered together with the accompanying figures of drawing.